Method for providing anonymous public key infrastructure and method for providing service using the same

Abstract

Provided is a method for providing an anonymous public key infrastructure (PKI) in a user terminal. The method includes receiving a real-name certificate from a real-name PKI service domain, requesting an anonymous certificate to an anonymous PKI service domain, and receiving the anonymous certificate from the anonymous PKI service domain. Accordingly, the method can ensure anonymity when a user uses a service by providing the anonymous certificate in association with the PKI-based real-name certificate.

1 . A method for providing an anonymous public key infrastructure (PKI) in a user terminal, the method comprising:
 receiving a real-name certificate from a real-name PKI service domain;   requesting an anonymous certificate to an anonymous PKI service domain; and   receiving the anonymous certificate from the anonymous PKI service domain.   
     
     
         2 . The method of  claim 1 , wherein the real-name certificate has a format defined by the following equation:
   CERT(N):=Sig CA     —     pr (N,N_pu)   
       where N is a real name of a user, N_pu is a public key corresponding to the user, Sig CA     —     pr  is a digital signature using a private key (CA_pr) of the real-name PKI service domain, a symbol:=is a definition, and CERT(N) is a real-name certificate of the user. 
     
     
         3 . The method of  claim 1 , wherein the requesting of the anonymous certificate comprises:
 generating an anonymous ID; and   requesting a user authentication and the anonymous certificate to the anonymous PKI service domain, based on the anonymous ID.   
     
     
         4 . The method of  claim 3 , wherein the anonymous ID has a format defined by the following equation:
   AID:=( g   PCA     —     pr ) A     —     pr  mod  n , or     AID:=( g   A     —     pr ) PCA     —     pr  mod  n      
       where PCA_pr is a private key of the anonymous PKI service domain, A_pr is a private key corresponding to the anonymous ID, mod n is a modular n operation, g is a password generator, a symbol:=is a definition, and AID is the anonymous ID. 
     
     
         5 . The method of  claim 3 , wherein the anonymous ID has a format defined by the following equation:
   AID:= A   —   pr (PCA_pr( G ))mod  n , or     AID:=PCA_pr( A _pr( G ))mod  n      
       where PCA_pr is a private key of the anonymous PKI service domain, A_pr is a private key corresponding to the anonymous ID, mod n is a modular n operation, g is a password generator, a symbol:=is a definition, and AID is the anonymous ID. 
     
     
         6 . The method of  claim 3 , wherein a message defined by the following equation is sent to the anonymous PKI service domain in order for the user authentication request
   ( K   CA     —     pu  mod  n∥E   K (CERT( N )))∥(AID∥A —   pu )
   
       where K is a secret key, CA_pu is a public key of the real-name PKI service domain, mod n is a modular n operation, // is a concatenation operator, E K  is an encryption routine using the secret key K, CERT(N) is the real-name certificate, AID is the anonymous ID, and A_pu is the public key corresponding to the anonymous ID. 
     
     
         7 . The method of  claim 6 , wherein the anonymous PKI service domain requests a secondary user authentication to the real-name PKI service domain in response to the user authentication request. 
     
     
         8 . The method of  claim 7 , wherein the secondary user authentication is performed by sending a message defined by the following equation to the real-name PKI domain service in order for user authentication request
     K   CA     —     pu  mod  n∥E   K (CERT( N ))   
     
     
         9 . The method of  claim 8 , wherein the real-name PKI service domain performs the user authentication requested by the anonymous PKI service domain in response to the secondary user authentication, based on the following equation:
   CERT( N )=? D   K ( E   K (CERT( N )))   
       where D K  is a decryption routine using the secret key K, and a symbol=? is an operation that is performed for comparing if both sides are identical to each other. 
     
     
         10 . The method of  claim 9 , wherein the real-name PKI service domain sends a response to the secondary user authentication to the anonymous PKI service domain. 
     
     
         11 . The method of  claim 10 , wherein the anonymous PKI service domain generates the anonymous certificate, based on the response to the secondary user authentication. 
     
     
         12 . The method of  claim 11 , wherein the anonymous PKI domain service authenticates a validity of the anonymous ID, based on the following equation:
   AID PCA =?AID N      
       where AID PCA  is the anonymous ID stored in the anonymous PKI service domain, AID N  is the anonymous ID generated from the user terminal, and a symbol=? is an operation that is performed for comparing if both sides are identical to each other. 
     
     
         13 . The method of  claim 1 , wherein the anonymous certificate has a format defined by the following equation:
   ACERT(AID):=Sig PCA     —     pr (AID,A_pu)   
       where AID is an anonymous ID, A_pu is a public key corresponding to the anonymous ID, Sig PCA     —     pr  is a digital signature using the private key PCA_pr of the anonymous PKI service domain, a symbol:=is a definition, and ACERT(AID) is the anonymous certificate of the user. 
     
     
         14 . The method of  claim 3 , wherein the anonymous ID is generated through a Diffie-Hellman key exchange or ECC key exchange between the user terminal and the anonymous PKI service domain. 
     
     
         15 . A method for providing an anonymous public key infrastructure (PKI) in an anonymous PKI service domain, the method comprising:
 receiving a request to issue an anonymous certificate, based on a real-name certificate from a user terminal;   requesting a user authentication to a real-name PKI service domain in response to the request to issue the anonymous certificate;   receiving a response to the user authentication from the real-name PKI service domain;   generating the anonymous certificate, based on the response; and   sending the generated anonymous certificate to the user terminal.   
     
     
         16 . The method of  claim 15 , wherein the receiving of the request to issue the anonymous certificate comprises receiving a request to issue the anonymous certificate, based on an anonymous ID. 
     
     
         17 . A method for providing an anonymous service using an anonymous public key infrastructure (PKI) in a service provider, the method comprising:
 receiving a request to provide an anonymous service from a user terminal by using an anonymous certificate generated through the method of any one of  claims 1  through  16 ;   receiving authentication information from an anonymous PKI service domain in response to the request to provide the anonymous service; and   providing a service corresponding to the request to provide the anonymous service, based on the authentication information.   
     
     
         18 . The method of  claim 17 , wherein the request to provide the anonymous service has a format defined by the following equation:
     K   ISP     —     Pu  mod  n∥E   K ( M∥H ( M )∥Sig A     —     pr ( H ( M )))
   
       where K is a shared key between a user of the user terminal and the service provider, ISP_pu is a public key of the service provider, M is a service-providing message, E K  is an encryption routine based on the shared key K, H is a hash routine, A_pr is a private key of an anonymous ID corresponding to the anonymous certificate, Sig A     —     pr  is a digital signature using a private key CA_pr corresponding to the anonymous ID, mod n is a modular n operation, and // is a concatenation operator. 
     
     
         19 . The method of  claim 17 , wherein the receiving of the request to provide the anonymous service comprises verifying the request to provide the anonymous service. 
     
     
         20 . The method of  claim 17 , wherein the receiving of the authentication information from the anonymous PKI service domain comprises receiving the authentication information including an anonymous ID corresponding to the anonymous certificate and an encryption value (E K (CERT(N))) of the real-name certificate (CERT(N)) corresponding to the anonymous certificate. 
     
     
         21 . The method of  claim 17 , wherein the providing of the service corresponding to the request to provide the anonymous service comprises:
 requesting a real-name authentication corresponding to the anonymous certificate; and   receiving a response to the real-name authentication.   
     
     
         22 . The method of  claim 21 , wherein the real-name authentication request comprises the anonymous ID, the service-providing message (M), and the encryption value (E K (CERT(N))). 
     
     
         23 . The method of  claim 21 , wherein the response to the real-name authentication request comprises the anonymous ID, the service-providing message (M), and an authentication acknowledge (ACK) with respec to the service-providing message (M).